As you probably know it is possible to open and close the first half of the front doors (the one closest to the windscreen) with a mouse click.

As stated in the manual:

4.6.11. Shutting Down the Bus1. Set the parking brake (3) and put the bus in neutral (9).2. Turn off all the fans (43, 45) and the auxiliary heater (37) andmake sure that the passenger lighting (39), engine coolingsystem (47) and windshield wipers (42) are off and the driverand passenger windows are closed.3. If you’d like to exit the bus, set the bus stop brake (10) andopen the front doors (11). You can then release the bus stopbrake.4. Turn off the lights and take the key out (4). You can now exitthe bus. You can close the front doors by clicking on the rightmaintenance opening next to the front door.

There is also an option in the graphics menu to make the driver dissapear from the bus.

If both functions would be combined it would realy look like the bus driver has shut down the bus and left home.

Yes it is, but that bus is Still yours. and your not handing it over, and that'd only be possible if the Human Character I.E your player was able to move freely wherever they wanted, but this function is not possible AS that'd strain Hardware to much. as Omsi already strains most computers and produces terrible amounts of FPS on all systems

But there is no need to hand over the bus. Just imagine you drive to the depot and shut down the bus. Than go to the external view and mouse click on the maintenance panel to shut the door (and at the same time remove the driver). Exit OMSI. The next time you start OMSI, go to the outside view and click that panel again to open the door and to automatically put the driver back at the steering wheel.

I haven't looked into it, but if you press the outside button to close the door after a long day of driving, then change to driver camera, press the pause button (usually P) and change back out it looks like the driver is gone. He gets back immediately after you press the pause button again.